These are Galvanometers built with Processing to be used with Arduino. The video shows 2 simple potentiometers connected to 2 Arduino analog inputs as voltage dividers for testing. Needle inertia was implemented by a digital low pass filter in the Processing code to smooth out the needle response simulating the D'Arsonval movement. Communication code uses only numbers no strings.

Hope you enjoy.

Here is the video: http://www.youtube.com/watch?v=5PUrhd8CK7g&feature=youtu.be

Perseverance is 90% of the solution. The remaining 10% is more perseverance.